-- I think your wife doesn't understand you.

-- On the c____, she understands me very well.

Our plane will      . All the passengers, please      your mobile phones.

   Everyone has worries. How do you deal with your worries? There is always something you can do to help yourself feel less worried. Sitting there worrying is no fun and it won't solve your problems.
   Grades at school are often a top worry for kids. ff you worry most about grades, ask yourself these questions:
●  Why are grades important? What do grades mean to me?
●  How do I get ready for class? Do I go over my notes even when there isn't a test?
●  Do I have a good place to do my homework?
●  Have I tried different ways of studying?
   If your worry is about a fight you had with your friend, you might write down al! the things you could do-write a note to him or her, invite him or her to watch a basketball game, say sorry to him or her and so on. Once you have a list of things you could do, you can choose one thing that could get your friend back.
   You can ask for help when you're worried. You can find someone to talk to, such as your parents, friends, and teachers.

在数学课上,老师提出如下问题:

尺规作图:作一条线段的垂直平分线

已知:线段AB

小芸的作法如下:

如图,(1)分别以点A和点B为圆心,大于 AB的长为半径作弧,两弧相交于C,D两点;(2)作直线CD.

老师说:“小芸的作法正确.”

请回答:小芸的作图依据是

____